sucker, common name for members of the family Catostomidae, freshwater fish related to the minnow and catfish families and like them possessing an intricate set of bones forming a highly sensitive hearing apparatus. Suckers range in size from 6 in. (15 cm) to 3 ft (90 cm). They have fleshy, sucking mouths and are sluggish bottom feeders, eating small aquatic animals and plants. The white, or common, sucker, found throughout North America, is an important food fish with firm, sweet (though bony) flesh. Buffalo fish are large suckers whose coarse, bony, nutritious flesh is also much used as food in the central states. The bigmouth buffalo fish reaches 4 ft (120 cm) in length and 65 lb (29 kg) in weight, the smallmouth buffalo fish sometimes attains 20 lb (9 kg), and the black, or mongrel, buffalo fish is intermediate in size. Other suckers are known as red horses, carp suckers, and freshwater mullets. Suckers are classified in the phylum Chordata, subphylum Vertebrata, class Osteichthyes, order Mormyriformes, family Catostomidae.